ABSTRACT
Three synthetic commercial insert repellents; Buzz-Off TM (30DEET); Cinq-sur-CinqTM (25IR3535 + essential oils) and prebutix TM(25IR3535) were tested in field conditions for their efficacy and persistence against mosquitoes in the forest area of Cameroon. During 48-days; 7; 569 mosquitoes belonging to four genera were collected: Mansonia spp (67.3); Anopheles spp (27.4); Aedes spp(3.8); and Culex spp (1.5). At the end of the 8-hours exposure period; the DEET-based repellent; Buzz Off TM produced the highest protection against Aedes spp; Culex spp and Mansonia spp. For Anophelines; results were more variable : PrebutixTM showed better protection against An. mouchetti; Cinq-sur-CinqTM was more efficacious against An. Funestus and An.ziemani; whereas Buzz-OffTM appeared more effective against An. Gambiae s.s. and An. nili. Efficacy and persistence parameters were estimated only for An. moucheti and Mansonia spp. The effective dosages (ED50 and ED95) as well as the effective half-life obtained with the DEET-based repellent were highly variable among replicates in the case of An. moucheti. For mansonia spp; the estimated EDO value for the DEET -based repellent was = 0.06mg/cm2. For the two IR3535-based repellents; the ED50 values varied from 0.06 to 0.10 mg/cm2; and 0.15 to 0.20 mg/cm2 for An. moucheti and Mansonia spp; respectively. Globally; the ED95 values values of the three repellents were around 1mg/cm2 except that of Cinq-sur-CinqTM which was ? 0.3mg/cm2 in the case of An. moucheti. The estimated effective half-lifes of the three repellents were approximately between 3 and 5h. Our results highlight the heterogeneity in the response of different mosquito species when exposed to the tested insect repellents; showing the relevance of evaluating efficacy and persistence profiles of different formulations in specific environmental contexts